Modern work vehicles, such as, tractors and wheel loaders, include a plurality of coolers to cool various fluids and gases. For example, one wheel loader requires a cooling system having a total of six coolers: an engine cooler (radiator) for cooling engine coolant; a transmission cooler for cooling transmission lubricating oil; a hydraulic cooler for cooling hydraulic fluid in a hydraulic fluid system; a charge air cooler for cooling intake air that is heated when it is compressed by a turbocharger; a cooling portion of an AC condenser for condensing freon gas used in an air conditioning system; and a fuel cooler for cooling fuel that is returned to a fuel tank from an injector pump. Each of these coolers operates by having air drawn through them to cool their respective fluid or gas.
One challenge in the design of work vehicles is the arrangement of these coolers to maintain adequate cooling efficiency. In one prior system, a plurality of coolers are spaced horizontally from one another, in series, in the direction of cooling air flow. Thus, ambient air enters the first cooler, then the second cooler, then the third cooler, and so forth. One drawback of this system is that only the first cooler receives relatively cool, ambient air, while each successive cooler receives air warmed by all of the preceding coolers. This arrangement reduces the cooling efficiency of the system.
Another challenge in the design of work vehicles is the arrangement of these coolers to reduce noise levels. Fan noise is a function of air restriction, among other factors, and can be very uncomfortable to the operator and to surrounding workers. In one prior system, a primary fan pushes air through a heat exchanger while a secondary fan located on the opposite side of the heat exchanger pulls the air through the heat exchanger. One drawback of this system is that the system includes two fans, both contributing to the noise levels of the cooling system. Another drawback of this system is that the primary pusher fan blows air directly into the heat exchanger. The primary pusher fan stirs up dirt particles and projects them at a high velocity into the heat exchanger, requiring more robust, and more costly, coolers.
Yet another challenge in the design of work vehicles is the arrangement of these coolers to receive clean ambient air. In some systems, air is drawn up from below the vehicle and/or through the engine compartment. This air is likely to contain relatively high dirt and particulate levels, which can result in clogging the cores of the coolers.
What is needed is a cooling system for a work vehicle that adequately addresses each of the above design challenges, wherein each cooler receives relatively cool and clean ambient air, the noise level is relatively low for both the operator and bystanders, and the coolers are not subjected to impingement by dirt particles driven by a pusher fan. The cooling system would also advantageously allow modular construction so that the cooling system can be pre-assembled at a remote location and then placed into the work vehicle during final assembly. The cooling system would also be located on the work vehicle in a position that allows optimum weight distribution and lower noise levels.